Seaweed Biodiversity in Ireland

If we regard as seaweeds the larger, attached marine species of the red, brown and green algae, slightly over 500 different kinds occur in Ireland.

Reds

Browns

Greens

Total

Ireland

274

147

80

501

Scotland

208

137

70

415

England & Wales

311

181

85

577

France

368

193

128

689

North Atlantic

620

329

256

1205

Numbers of seaweed species (red, brown and green) occurring in selected areas and in the whole of the North Atlantic. Data from Guiry (1996, AlgaeBase).

Although more species occur in England and Wales (taken together) than
in Ireland, less are found in Scotland, and, considering smallness of the
island, we have a remarkably high proportion of the marine algae of the
whole of the North Atlantic basin. Many of these algae are relatively obscure
species, known only to a handful of experts world-wide. Since 1979, our
knowledge of Irish seaweed biodiversity has increased considerably (see
Table above), due largely to more widespread subtidal investigations. Extensive
taxonomic revisions have resulted in a seeming decrease in the total numbers
of green algae, but the large increase in the red algae is mainly due to
discoveries of previously unknown species, particularly in the subtidal
of the west coast. Further taxonomic studies of our marine algae are needed,
particularly of some of the supposedly well-known genera such as Fucus.